Paenibacillus larvae enolase as a virulence factor in honeybee larvae infection

Paenibacillus larvae is a gram-positive spore-forming bacteria, causative agent of American Foulbrood (AFB), a severe disease affecting larvae of the honeybee Apis mellifera. In an attempt to detect potential virulence factors secreted by P. larvae, we identified an enolase among different secreted proteins. Although this protein is a cytosolic enzyme involved in glycolytic pathways, it has been related to virulence. The aim of the present work was to evaluate its role during the infection of honeybee larvae. Toxicity assays showed that enolase was highly toxic and immunogenic to honeybee larvae. Its production was detected inside P. larvae vegetative cells, on the surface of P. larvae spores and secreted to the external growth medium. P. larvae enolase production was also confirmed in vivo, during the infection of honeybee larvae. This protein was able to hydrolyze milk proteins as described for P. larvae, suggesting that could be involved in larval degradation, maybe through the plasmin(ogen) system. These results suggest that P. larvae enolase may have a role in virulence and could contribute to a general insight about insect-pathogen interaction mechanisms.     

番茄疮痂病菌T3小种抗性的QTL分析

 利用由抗番茄细菌性疮痂病菌T3小种材料PI114490构建的回交自交群体分析其抗性遗传规律,鉴定与抗性连锁的分子标记。从516个SSR、SNP和InDel标记中筛选到72个在亲本之间有多态性的标记。单标记分析结果显示,PI114490对T3小种的抗性由分布于1、3、8和11号染色体上的多个QTL控制,其中11号染色体上的QTL能提供高达56.5%的抗性;分析各回交自交系的基因型发现,这些QTL之间可能存在互作。这为进一步研究PI114490对T3小种的抗性机理和抗病育种提供了参考依据。     

EPOXI at comet Hartley 2

Understanding how comets work--what drives their activity--is crucial to the use of comets in studying the early solar system. EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation) flew past comet 103P/Hartley 2, one with an unusually small but very active nucleus, taking both images and spectra. Unlike large, relatively inactive nuclei, this nucleus is outgassing primarily because of CO(2), which drags chunks of ice out of the nucleus. It also shows substantial differences in the relative abundance of volatiles from various parts of the nucleus.     

In vitro evaluation of flavonoids from Eriodictyon californicum for antagonist activity against the bitterness receptor hTAS2R31

The leaves of the native North American plant, Eriodictyon californicum, were once used to mask the bitter taste of pharmaceuticals, an application currently of importance. Ten flavonoids (1-10) were isolated from the leaves of E. californicum, of which the structure and absolute configuration of 6-methoxyhesperetin (8) were assigned for the first time. In addition, the absolute configurations at C-2 were established for 4'-isobutyrylhomoeriodictyol (3) and 6-methoxyhomoeriodictyol (7). Using a cell-based assay, it was determined that the 7-methoxylated flavanones, sakuranetin (2) and 6-methoxysakuranetin (9), and the flavone, jaceosidin (10), are antagonists of hTAS2R31.     

Surface melt-induced acceleration of Greenland ice-sheet flow

Ice flow at a location in the equilibrium zone of the west-central Greenland Ice Sheet accelerates above the midwinter average rate during periods of summer melting. The near coincidence of the ice acceleration with the duration of surface melting, followed by deceleration after the melting ceases, indicates that glacial sliding is enhanced by rapid migration of surface meltwater to the ice-bedrock interface. Interannual variations in the ice acceleration are correlated with variations in the intensity of the surface melting, with larger increases accompanying higher amounts of summer melting. The indicated coupling between surface melting and ice-sheet flow provides a mechanism for rapid, large-scale, dynamic responses of ice sheets to climate warming.